1. Field of the Invention
The present invention relates to a method of making a molded wood article and more particularly to the use of ammonium salts in the fabrication of molded wood articles having superior physical properties.
2. The Prior Art
It is known to the art e.g., U.S. Pat. Nos. 2,237,048 and 2,754,730 to fabricate molded articles such as plates, trays and cups from particles of cellulosic material, and in particular ligno-cellulosic materials, such as wood flour by blending the particles with a thermosetting resin powder such as melamine formaldehyde or a thermoplastic resin powder such as polyethylene and then compressing the mixture of resin and wood particles in a mold at elevated temperatures and pressures to form the desired wood article.
It is also known to the art, to prepare molded wood products from wood particles wherein the wood particles are treated with a variety of chemical agents such as a strong alkali (U.S. Pat. No. 2,708,637), an ammonium salt of a strong acid such as ammonium phosphate (U.S. Pat. No. 2,779,683), a dilute solution of a strong acid such as ammonium chloride (Tr. Ural'sk Lesotckh Inst. No. 19, 1966, pgs. 39-43) or liquid ammonia (U.S. Pat. No. 3,305,499). After treatment with these chemical agents the wood particles are placed in a mold of suitable shape and the particles are compressed at elevated temperatures and pressures to prepare the desired molded article.
Although the strength and integrity of molded wood products prepared using chemically treated wood particles have been reasonably good, they have not been considered commercially comparable to molded wood articles obtained using a resin binder.